CCK and Alzheimer disease: Studies have reported that interneurons with calcium-binding proteins such as calretinin might overcome the excitotoxicity induced by increasing intracellular Ca2+ concentration (Mikkonen et al. 1999), whereas interneurons without calcium-binding proteins but expressing neurotransmitters like CCK and SST are more likely to degenerate in AD (Saiz-Sanchez et al. 2015).